\\[-1.8ex] Soil Heterogeneity & $-$0.275 & $-$0.754$^{***}$ & $-$0.594$^{***}$ & $-$0.479$^{***}$ & $-$0.373$^{***}$ & $-$0.376$^{***}$ \\ 
  & (0.217) & (0.144) & (0.132) & (0.137) & (0.111) & (0.101) \\ 
\\[-1.8ex] 
Oster $\delta$ for $\beta=0$ &  & -2.93 & -5.73 & -10.65 & -249.49 & 352.51 \\ 
Observations & 19,881 & 19,881 & 19,881 & 19,881 & 19,881 & 19,837 \\ 
R$^{2}$ & 0.001 & 0.352 & 0.392 & 0.407 & 0.421 & 0.428 \\ 
